Other Fathers
by GreenSneakers1998
Summary: A murder in east Brooklyn. It's not the first time, and it won't be the last, but this case is different. When a 6 year old from Boston is kidnapped in the wake of a double homicide Castle and Beckett find themselves being forced to co-operate with an FBI agent Kate has very specific history with to solve a case that hits far too close to home. Married/post-ttool fic. OC child.
1. Chapter 1: A Way to Go

Katherine Beckett trudged up to the scene, prepossessing and seemingly out of place in a red coat and boot heels. A grey, crime-ridden estate in Brownsville is not where she had wanted to be at 9:15 this Friday morning, "So what's the deal with this guy?"

Ryan and Espo had arrived 15 minutes earlier to find Lanie already standing by with a clipboard to begin her report. None of them were particularly thrilled to be out in the damp east coast cold either.

However, they were the lucky ones. The young man lying crumpled on the ground was pale-skinned with a shock of dark hair. His white shirt was saturated with blood, two fair sized holes visible in the fabric, a jagged pool of red creeping through the cracks in the concrete around his corpse.

Lanie didn't look up from her clipboard, but gestured to the body, "Two rounds to the lower back, large calibre, long range. The shooter was messy, neither shot killed him instantly, poor guy bled out right here."

"Lying out in the cold, alone, two holes in your back? What a way to go." Ryan commented, arms folded as his blue eyes trailed up and down their victim sympathetically.

Esposito was crouched beside the body, "Probably shot him whilst hidden down the side of the houses. I can see if the security-"

"Where's Castle?" Ryan interrupted, seemingly only just realising there had been no snarky comments or questionable theorising. He peered around Beckett as though he expected the writer to be hidden there.

"Felix has a school assembly this morning. We thought at least one of us should show up." Beckett sighed, she actually preferred crime scenes and dead bodies to school halls and pta moms, but Felix had been chattering on about this assembly all week. He was playing an Alien. For Felix that was a dream come true. Why, exactly, there was an Alien in an assembly about the Boston Tea Party was a mystery she may now never solve. Maybe if they finished up quick she could catch the end.

"Sorry to call you out here, Honey. I know Felix wanted you there." Lanie looked genuinely apologetic.

"It's okay. He understands." Beckett lied; he was six of course he didn't understand. He'd sat on the stairs next to his dad and they'd both pouted at her as she'd pulled on her boots. Kissing them both on the head she'd repeated the word 'sorry' more times than she ever thought possible before closing the door to the loft and to their jutting bottom lips.

"Do we know who he is?" She brought their attention back to the man sprawled across the concrete.

"No Wallet. No ID." Ryan shook his head, "All I found was a couple of tissues, a bottled water, and car keys. Can tell you this though, these clothes are nice, really nice. Those shoes are Kurt Geiger, expensive and British. This guy's not from this neighbourhood, that's for sure."

Espo stared at his friend, a judgemental eyebrow ascending, "Kurt Geiger?"

"Jenny… uh," Ryan stumbled, "I got her a pair for her birthday. Cost near $200." The man flinched at the memory.

Esposito grimaced, "Man, that's ridiculous."

Lanie sighed, "No, Javi, that's love."

Esposito opened his mouth to reply, most likely to defend himself. Probably planning to mention some of the expensive gifts he'd given her over the years and subsequently embarrass himself.

"So, 'no wallet'?" Beckett repeated, loudly.

"You think this was a mugging gone south?" Espo's brow furrowed.

"Then why wouldn't the mugger take his car keys? And he was shot from at least 20 meters away, in his back, if this was a mugging it should have been point blank."

"Maybe our vic tried to get away, he's running, muggers a rookie, gets scared the guy's gonna go to the police, he shoots him out of fear." Ryan theorises.

Kate bit her lip, looking to Lanie, "No defensive wounds?"

The M.E. shook her head, "Nope, the abrasions on his face and hands are from contact made with the road when he fell."

Beckett voice was quieter as she considered the possibilities, "All my instincts say our vic had no idea a gun was pointed at him. This was personal. But why was he out without a wallet, unless…"

Her gaze fell on a set of stairs to her right, leading underground, like stairs to a subway station.

"Unless he wasn't." Kate concluded, "Ryan was he holding the keys?"

"Yeah, why d-"

"I need them." Beckett held out her hand.

Kevin Ryan dropped the paper bag into her palm and waited to see what she would do.

"Ryan, Espo, back me up. Lanie can you ride with the body back to the morgue? I want him autopsied ASAP."

"Sure." Lanie said to Kate Beckett's back as the three detectives hurried down the stairs to her left, not waiting to hear the M.E.'s response.

It was dark, a concrete cavern. The artificial light from the grimy overhead lamps flickered and shifted, glancing dully off mismatched rows of old vans and battered Chevys'. The air was heavy with the scent of fuel, must and cigarettes. This was exactly the sort of place where bad things would happen if this was one of Castle's books, Beckett thought to herself.

She slowed as she reached the centre of the lot, gun in one hand, pointed at the floor, a dead man's car keys in the other. She lifted the keys up and pressed down hard on the center button.

A flash of light and loud click two rows over sent a shot of adrenaline through Beckett's heart.

"Nice." Esposito muttered.

The trio jogged over to the vehicle.

"Smart car, a brand new Ford's not too common in a place like this." Ryan commented looking around at the other, less aesthetically pleasing vehicles.

Beckett seemed indifferent to his observation. As soon as she was a few meters away she saw something that made her blood run cold. Red spotted the inside of the passenger-side window, pooling and drying at the base of it. Beckett swore, reaching into her pocket for her phone.

"Ryan go, don't let Lanie leave. Get CSU down here. I want this whole lot swept, now!" Kate Beckett held the phone to her ear, hearing it go to hold, waiting to call in the second homicide.

Esposito tugged open the driver's door and Ryan sped off.

"You got anything? Who are they?" Beckett's teeth were gritted.

"It's dark in here but uh… I'd say young white female. She's wedged in-between in the two front seats, like she was trying to get into the back when she was shot in the same way as our vic. Two rounds to the back. Think I found our John Doe's coat… and wallet."

He handed it to Beckett swiftly, going back to gently poking around in the car.

Kate flipped open the wallet, pulling out a blue credit card, _'Simon. .'_ She flicked through, a modest wad of green notes confirming that this was definitely not a robbery. That's when she discovered a small pocket in the back of the wallet, only big enough for a couple of receipts or a bank note, in this case there was a small photo. It was no bigger than ticket stub. It was a family. Two Caucasian adults, a man and woman, both young, and a child, a boy that looked to be about six years of age, all of them smiling. Beckett recognised the man as Simon. , their original victim.

Her heart raced as she went round the other side of the car, peering inside. The woman slumped over the gearstick was the woman from the photo. Beckett steeled herself.

"Espo…" She gulped, feeling a little faint. She couldn't handle this. The little boy was the same age as Felix.

"Yeah?"

"Please tell me there's not a little boy in the back of this car?" She stepped back, eyes wide, breathing shaky. Child Homicides were the worst, she'd only dealt with two, and not catching the killer, it had taken everything out of her. Beckett wasn't sure she could handle dealing with the murder of boy not so different from her own son.

"Uh…"

"Espo." She added desperately.

He reached for the flashlight at his hip, pushing his thumb to the button a bright light burst forth. The detective leant over the driver's seat awkwardly, careful not to contaminate the crime scene, "No. No. But there's an empty booster seat." Esposito confirmed, relief obvious in his tone.

Kate let out a shuddering breath.

"Why'd you ask?" He said, coming to stand up straight beside her, turning off the flashlight.

"I know what we're looking at here." She pursed her lips.

Esposito waited.

"If you're trying to get away from someone with a gun at the drivers window, and you're in the passenger seat, where do you go?"

Javier looked at her as if he wasn't sure whether or not it was a trick question, "Out the passenger door?"

"Exactly. Except she was trying to get into the back seat."

"She wasn't trying to get away." Esposito added.

"There is only one reason that a woman would throw herself into the back seat of the car when she has a clear route out and a gun at her back." Beckett paused, "She was a mother, and her child was in the back seat."

Beckett's eyes were burning with the effort of holding back, her jaw tight. She had never cried at a crime scene before… but this. This was so close to home. She looked down at the corpse of the woman draped over the seats, limp. Kate would have done the same for Felix. Hell, she would do the same for Alexis, sure, but, it was different when a child was small. When they were vulnerable. Her son had no comprehension of real evil. The kid called a lack of cookies, or cancelled playdates 'evil', with no true understanding of what and who that word actually represented in Kate's eyes. Men like 3XK, like Bracken. Evil that was all-encompassing and immortal, Kate Beckett had looked it in the face so many times it had just become part of her life. Seeing the pure innocence in children, in her son, in his friends, reminded her that there were still people without scars like hers that needed protection. She would keep him safe from the dark side of humanity as long as she could.

When Felix had been born Kate had made Rick promise, promise that they would keep their family life separate from their work life. She had expected him to disagree, to insist they could have their cake and eat it too, but he hadn't, he'd regarded his son's tiny scrunched-up newborn features and nodded. They had kept Felix away from the precinct as soon as he was old enough to see anything beyond his own toes, scared he would see something on one of the murder boards he would not be able to unsee. Kate kept case files locked away when she brought them home, moved Rick's more graphic crime novels to the top shelves before Felix had been old enough to stand, warned the boys and Lanie never to talk about cases around her son. As a result, Felix had, until recently, little idea what his parents did, or what they were capable of. He was also much more safe.

Keeping Felix out the public eye had been a task. An announcement of his birth had been released personally by them so that it wouldn't be 'news'. Then, a year ago, The New York Hedge had named them Manhattan power couple no.3, mentioning their _'adorable 5 year old son Felix Roger Castle; the spitting image of his father'_ and that it would be _'interesting to see what traits he's inherited from his mother. No doubt bright and charismatic, with a successful novelist and philanthropist for a father, and a detective favoured to be New York's youngest ever female senator for his mother, he is one to watch when considering the future of New York.'_ A picture of their son had been published. A bright candid of him in his school uniform walking past a bank in upper Manhattan, his little hand in his father's. Castle had gritted his teeth and remembered that day; he'd picked Felix up from school promising him a hot cocoa, but that he had to be good and they had to quickly drop something off at his publishers first. There would have been cameras outside that office building. It was a highly regarded office space, a bank on the first floor, very central, lots of high profile organisations with equally high profile clients used floors in that building. Chances were the photographer hadn't even been waiting for him, and that they'd just been looking to make a quick buck, snatching at the opportunity when it arose.

'New York's no.3 power couple,' had come down like a ton of brick on both the Hedge and the photographer in question, pressing charges, making an example out of them. It was too late though, the paper, the story, it was already out in the world. Printed in ink and posted to news sites it was impossible to erase. A few more sites had picked it up before their lawyers had managed to pass the injunction on the photo.

For months Castle had to endure questions in interviews, mentions in his fan mail, and compliments from strangers about his son. Primarily well-meant or not it was terrifying and Castle had politely refused to discuss Felix. Eventually people got bored and the interest died slowly away.

Kate Beckett and Richard Castle had their fair share of enemies, some of whom who might even stoop so low as to abduct or even harm a child to get what they wanted. It was the reason they'd kept information on Felix private. It was the reason that they'd broken their number one rule, one they'd made the day he was born, when the New York Hedge story broke: _'Do not bring Felix to the precinct.'_ They'd been paranoid, terrified for Felix's safety, and what was safer for a cop's son that a building filled with cops? So, when he wasn't at school, and Castle had to write, the boy had made himself at home in the break room where his mom could keep tabs on him. Luckily he wasn't big enough to see over the partition, so he couldn't see the murder boards. His mom had laid down the law with him; number one was 'stay out of the bullpen.' number two was 'do not touch anything that isn't yours.' And number three was 'don't wander off.'

… 'stay out.'… 'don't touch'…'don't wander off.' Why had she even bothered? He was Castle's kid too.

She'd had had him handed back to her by disgruntled but amused colleagues more times than she could count. They'd found him messing with the pots in the cafeteria kitchen, playing spy under a desk in narcotics, messing with the earmuffs in the arms range, and… hiding (to scare Lanie) in a _morgue freezer_? That last one had been the talk of the precinct for months. Mini Castle seemed to liven up the place even more than big Castle.

Felix Castle was precocious, smart, and determined, but he was still not much more than a baby. Beckett couldn't bear to imagine him in the same situation as this child. His mother murdered in front of him, his father dead too, taken from everything and everyone he knows. If it was Felix… 'if…' Beckett felt nauseated at the mere thought of it. She had to save this little boy or she'd never be able to live with herself.

"Kid's gone. Think this is what it looks like?" Esposito asked.

Beckett began to walk away, handing him her phone, seeing Lanie descending the steps at the other end of the lot, "Call it in as a double homicide and kidnapping."

…..

Kate Beckett tried not to charge through the crowd, very aware of small people and little feet. She knew she must look intimidating and tried to loosen up her shoulders by rolling them, not that it did much good. She still looked like she'd seen a ghost. The muscles in her face were taught, eyes dark.

The school auditorium was full of bright colours and children's laughter, all which seemed out of place in a world she knew to have such a dark side. This brightness, this side of her world, it was what kept the darkness from tightening its grip on her. It used to have such a strong hold on her but those days seemed so distant now it was like someone else had lived them. Her life used to be consumed by horrors; every day she would dance with death, shake hands with murderers, hopefully lock a pair of cuffs around their wrists too, and then go home to sit in the dim light and fixate on 'how?'. What could persuade a person to commit such a heinous act?

Now when she came home she was too preoccupied with her colourful family; a mother-in-law who flittered around like a beautiful red butterfly, a strong-willed step-daughter with a kind heart and a insuppressible intellect that drove Kate's husband to the brink of madness with worry, a son that forced her to ponder first grade math and dinosaur-shaped chicken at home rather more than murder, and, of course, a husband that seemed to orbit her, so often in her presence with a smile in his eyes and a witty quip on the tip of his tongue. She had found home, and the thought of losing it, of losing Felix especially, she couldn't, and didn't want to, imagine.

"Kate!" Castle's voice met her ears, grounding her a little, she'd stopped right in the center of the auditorium so it hadn't take long for him to notice her. He was stood amongst a group of well-groomed elite parents; moms with perfectly styled hair, and dads with creaseless shirts. Small, first graders in blue and maroon uniforms were scattered around, some hovering around their parents, some playing with their friends.

Kate recognised the couple Castle was talking with; Alan and Heather Teller, lawyers with a 6 year old girl called Annie in Felix's class, and a son in third grade. The perfect all-American family stereotype. The other man was Tom? Ted? Something beginning with a T… his son was in Felix's class too, but Kate couldn't remember the name.

"Hey," She breathed, entering the group, sidling up to Castle. He placed his hand on her waist. "Where's Felix?"

' _Sir…' Kate had begun, fidgeting in front of Captain Gates' desk, 'Given the nature of this case I was wondering-'_

' _Go, Detective,' the woman interrupted her in a softer tone than Kate was used to from the Captain._

' _Sir?'_

' _Right now you can't concentrate, you need to see your son more than we need you. Esposito and Ryan can look into our victims, that'll take at least a couple of hours.' Gates had looked at her pointedly._

 _Beckett had been unable to hold back her grateful smile, 'Thank you sir.'_

Her husband nodded to the corridor leading off to their right, Felix's classroom was the third door, "Dynamo's getting changed, everyone thought his costume was awesome by the way. I'm saving the 'I told you so' for later. He'll be out in a minute." Kate made to go, her expression still strained, but Castle stopped her with a hand in hers, "Hey, you okay?"

Kate kept her voice low, "The call I got this morning, turns out its double homicide… and a kidnapping."

Castle clenched his teeth, "Little kid?"

Beckett nodded, "Little boy, about 6 years old. Both parents took a couple of fatal rounds to the back trying to protect him."

Castle's grip on her loosened completely, visibly pained by the news.

"You came!" By the time she turned around Felix had already hit her legs at full force. Castle pressed a hand to her back with a smile to steady her as she wobbled.

"Hey, Turbo, of course." Katherine Beckett looked down at Felix's face. His bright smile was akin to a thin smirk, a mischievous glint always in his eyes in a way that was distinctly Richard Castle. Kate remembered the first time Felix had smiled, still just a small baby, and he'd looked just like his dad, her heart had stopped. She'd yelled for Alexis, and the girl had thundered down the stairs to excitedly confirm that yes, she agreed, Kate wasn't just imagining it.

"Stay for the picnic?" Felix gripped his mother's arm tight and jumped up and down, "Pretty please!" His wide, green eyes boring into her, the previous events of the morning, and the indignant flare of his nostrils, all making her weak to refuse him.

"Looks like it's going to quite the event." The guy who Kate thought was called Tom or Ted finally spoke up. If their audience had overheard her and Castle speaking about work they had elected to stay out of it.

Alan Teller smiled wide, "Heather made her famous white chocolate brownies." He gave his beaming wife a fond look.

Castle gulped, he did love white chocolate brownies.

"I…" Kate looked torn, they should be getting back to the precinct.

The look in Felix's eyes was heart-breaking.

"Come here." Kate whispered, crouching to his level and locking her arms under his rump, lifting him up. He wrapped his arms around her neck and tucked his head in instinctively. He seemed so small still, but it was getting harder to carry him like this, like she had when he was a baby. A few more years and she wouldn't be able to manage it anymore, and he wouldn't want her to. That day couldn't come slow enough.

"I want to Little Man, but there's another little boy we need to go help."

"Why can't his own mom and dad help him?"

"He…" Beckett faltered, her mind going back to the broken bodies of Mr and Mrs Ryder, "doesn't have a mom and dad."

"Why not?" The boy murmured into her shoulder.

"That's what I'm trying to find out." It wasn't a lie, she'd gotten good at not lying whilst still not telling her son the gruesome truth. Felix knew she 'caught bad people', but he didn't know the horrors she saw every week. He didn't know he was her anchor, the one she had sorely needed for so long. He reminded every day her why she'd become a cop in the first place; because of the people she loved, and some fierce need to protect them. Felix was like his dad in that way, good at warding off the darkness. Castle kept her amused on the job, he protected her from letting the seriousness of murder crush her underneath the sheer weight of its anguish. He'd once said _'Let's not let a little thing like murder get in the way of having a good time.'_ And despite its jovial, jokey nature it had stayed with her. Whenever she saw a body she reminded herself that their death was just another reason to keep on living, because they couldn't anymore at least someone else should. Living for those who've passed on makes a lot more sense to her than letting their deaths consume her.

There was a pause.

"Okay." Felix agreed, and it felt like a blessing.

She put him down and straightened his uniform as she spoke, centring his tie, "Gram's picking you up today. I'll see you at dinner. Help your sister, but no touching the knives this time okay."

The boy huffed like she'd just said something completely unreasonable.

"Be good." She pressed a kiss to his head.

The boy's expression morphed into a smirk, "You too."

Kate raised an eyebrow, quietly saying, "I will, it's your dad we have to worry about."

Felix giggled, nodding, "Yep!"

"I love you Felix." She said, the words were to comfort her more than him, having needed to say them so desperately for the past couple of hours since she'd found that blood splattered empty booster seat.

"Love you." The boy said absently, his gaze wandering behind his mother to where the food was being laid out. The words were a natural end to the conversation to him and held little real meaning, they were just a certainty. Felix had never known a lack of this particular emotion. He had grandparents, parents, and a sister, all of which would be willing to take a bullet for him just as Mrs Ryder had for her little boy. In fact, there was a whole floor of the 12th precinct, a good 15 homicide detectives, their subordinates, and a captain, all who'd known him since he was no more than a few weeks old, who would do everything in their power if the time ever came. If anything ever happened to Felix, god forbid, there would be no problem finding people willing to do anything and everything to get him back.

The Ryder's boy played on her mind, all blond curls and freckles, he was so different from Felix but it still hit too close to home. Kate wondered if there was anyone else out there looking for this other little boy, a grandparent, a friend, or if maybe she was all he had now.

…

"Should have told Felix to sneak me one of those brownies." Castle grimaced at his rumbling stomach.

Beckett ignored him, eyes trained on the murder board. She was missing something. She could feel it.

Javier Esposito shot Castle a withering look from where he was leant against the wall by the board, "And now you're all for encouraging the 6 year old to steal?"

"It's not stealing," Castle defended himself, turning his nose up at his friend, "I would never encourage my children to partake in anything illegal."

"Liar." Espo muttered.

"You taught Alexis to pick a lock." Beckett said in a monotone voice, eyes still on the board.

"It was for research." Castle stressed the word 'research'.

Beckett shot her husband a look, "She was ten."

Castle smiled sweetly, "And look how wonderfully honest she turned out to be. Just goes to show that experience of all kinds, good and… questionable, are important ingredients in producing a balanced individual."

"You think our shooter killed these two people and kidnapped their kid because his daddy didn't let him play with tension tools?" Beckett crossed her arms, eyebrow raised.

"It's improbable, not impossible." Castle conceded, "And why are we assuming the shooter is a he? Perhaps it was a desperate mother who'd lost her child. Unconvinced of her own son's death she sees a young boy, the Ryder's son, who looks just like her own, walking hand in hand with two strangers. She follows them, gun in hand, to get her 'son' back. Waits for the right moment and then strikes, killing the people she perceives to have taken her son and kidnaps Ryder junior.

Javier and Kate were staring pointedly at him, as enamoured by his stories as they ever were, which is to say not very.

"Well, there is one thing you touched on that we need to find out to crack this: Why would anyone be willing to kill to kidnap this particular 6 year old?"

Before Castle could answer with another wild theory a file was slammed down next to him.

"Well I can't answer that but I do have some answers." Ryan began, "Our vics are Simon and Fiona Ryder, sons name is Barney Ryder, six years old, as far as we know they went missing from their home in Boston 3 days ago. Simon's a big-shot lawyer, owns the firm Ryder and Brooks, Fiona's a Communications Exec there. Company's been looking for them since 10:00 am Tuesday. Secretary says they tried to call Simon and Fiona numerous times but their phones went straight to voicemail."

"They were obviously into something." Espo concluded.

"That's not all. There were a bunch of bags in the trunk. Food, clothes-"

"Impromptu holiday?" Castle suggested sarcastically.

"Yeah, not so much." Ryan continued, "Bags also contained fake passports for all 3 of them, and Mexican peso, 50,000 good old American dollars' worth."

"They were running for the border." Kate looked to Castle.

"Then maybe whatever they were running from caught up to them." He said, mind racing. This just got more intriguing by the minute.

"Espo, look into this guy's company financials, client list, I want to know if there was anything weird going on." Kate turned to Ryan, picking up the file he'd dropped on her desk, "Ryan look into their family life, find any relatives you can, interview them, see if they can shed some light onto what was going on."

"Detective!" Gates called from the door of her office, summoning Beckett, and in that way Castle as well.

Beckett was surprised to find another person waiting inside the office. She hadn't seen him in so long she almost didn't recognise him. Will Sorenson was older now, squared-jawed as he ever had been but with a trim beard. His hair was longer, streaks of silver barely noticeable, but definitely there. He'd put on some weight around his mid-section. The slim, dark suit didn't seem to fit as well anymore. Even though he'd changed so visibly there was something very familiar and certain in his eyes, still that same piercing blue. Then again, that was why she'd been attracted to him, he'd been familiar, someone like her, the safe option.

"Kate Beckett," Sorenson whipped his hand out his pocket to offer it in a friendly handshake. Kate had to admit she was relieved since she'd been momentarily afraid he'd go in for a hug. That would have made the situation even more awkward.

"Hey, Will." When he let her hand go she backed away, right into her husband's chest. He'd been stood right behind her, no more than a few inches, staring Sorenson down like a pit-bull.

"Castle." Sorenson offered Castle a respectful nod.

After a moment Castle's solid façade softened and he returned it.

"As we know now Detective," The Captain looked dubiously from the couple to Sorenson, "The Ryders were Massachusetts residents, making this a Federal case, a Federal Kidnapping. Agent Sorenson and his people will be taking point on this but he's agreed to the participation of the 12th."

"Has he now." Castle muttered through gritted teeth. Kate's elbow promptly hit him discretely in the liver. Wincing, he pursed his lips.

"I expect you to follow his lead on this," Gates looked pointedly at the precinct's resident writer and man-child, "I'm talking to you, Mr Castle, any of your antics and I will send you home."

Kate bit her lip, desperate not to laugh at Castle's scandalised expression.

"We good here?" Gates looked between the three of them.

"Yes, Sir." Beckett nodded, praying for Castle to keep his mouth shut.

"Ok, that's all." The Captain sighed, sitting back down at her desk.

The three of them filed out the office. Kate felt the familiar press of Castle's hand on her lower back and rolled her eyes. A week of male posturing between her husband and ex-boyfriend was really not going to help with the investigation.

Esposito caught her eye as she walked through the door frame and, seeing Sorenson, wiggled his eyebrows conspiratorially. Yeah. This was going to be hell.

It was another 35 minutes before Will asked after her. She'd distracted him with a briefing on what they'd uncovered so far, not eager to talk about her personal life. Her marriage to Castle was bound to bring with it a slew of questions she didn't want to answer.

But then Castle had gone to make coffee and left her 'unguarded'.

"How you been, Kate?" How did she even begin to answer that? So much had happened since they'd last seen each other. She'd nearly died numerous times, solved hundreds of cases, fallen in love, moved apartment, gotten married, and had a child. All those ups and downs, where did she begin?

"Good. You?" It was the stock answer. The safe one.

"Same." Sorenson's hands were in his pockets. He always used to do it when he was nervous to stop himself fidgeting.

Beckett continued to write on the murder board, the squeak of the marker pen, the hum of computers, and muttered background conversations filled the quiet moment between them.

"So you uh…" Will began.

Kate braced herself, eyes rolling to the heavens.

"…married Castle?" He finished.

"Yep." She took a deep breath and then continued to write.

"You know I-" Will went to continue talking.

"Will." Kate Becket huffed, turning to face him, trying to look as calm as possible, "I do not need this right now, please stop, I do not want to spend this case wedged uncomfortably between you and Castle."

"Kate." Sorenson tried not to squirm under the intensity of her gaze. "I was just gonna say I saw it coming."

Beckett was taken aback.

"Not the marriage thing, but I always knew something was gonna happen with you guys."

"Who guys?" Castle asked, catching the end of Sorenson's sentence as he placed Beckett's blue coffee mug on her desk and cupped his hands around his own.

"We need to go to Boston, there's no way we're going to be able to solve this without finding out where your vics and my kidnap victim started out." Sorenson diverted attention from his previous words with finesse.

"Sorenson's right." Kate sighed, picking up her coffee, "The key lies in Boston. We can't perform a time-sensitive investigation properly from a desk in NY."

"Field trip!" Castle grinned.

"We can take my car." Sorenson said.

Kate's face fell, "Boston can take 7 hours in a car, and we'll have to stay overnight."

Both men paled at the idea of 7 hours stuck in a car together.

Beckett continued, "I told Felix we'd be home for dinner. He's helping Alexis make Carbonara tonight, I said since it's a Friday he could-"

"Stay up to play laser tag and watch a movie. Yeah, I know." Castle looked completely and utterly disheartened. If there was one thing Richard Castle couldn't bear it was letting his kids down.

"I guess I could… go by myself?" Sorenson suggested, his hands back in his pockets, awkward at the mention of his former girlfriend's son.

"No, Will. Thanks." Kate dismissed the idea. It was unprofessional to let Sorenson do her work for her. Beckett felt awful about Felix though, not to mention she'd really been looking forward to tonight herself.

"He'll be fine." Castle reassured her, "We'll do it next week instead. My mother can look after Felix for a day or so. After all, she raised me and I turned out okay."

Kate narrowed her eyes at her husband, "I… uh… I'll call my dad, he can take Felix out somewhere tomorrow to distract him."

Castle quirked his head at her.

"I don't want Martha to feel overwhelmed," Kate shrugged.

There was a pause.

"Guess I'll go bring the car round then?" Sorenson made to make a move.

"Oh." Castle's eyes widened, hands going up in a gesture of realisation.

"What?" Sorenson said, wondering if he was going to regret asking.

"Kate, you remember when I bought that helicopter to do some research for Electric Heat?" He gapped at his wife excitedly, eyes shining.

"Yeah?"

"It's still on the helipad. That's only 30 minutes away."

"You bought an entire helicopter for research?" Sorenson said, staring at Castle in a mixture of awe, disgust, and disbelief.

"Yes," Castle shot him a withering look, "buying half of one didn't make much sense."

Will gritted his teeth.

"That's still 4 hours there and back we won't get home in time, Castle." Beckett said, taking a sip of her coffee.

"No, but it means we don't have to spend 7 hours stuck in a car together which I think we can all agreed _no one_ here is keen on."

There was silence, and that was enough of a response.

"Ok then," Castle smirked, "I guess we're helicoptering to Boston."


	2. Chapter 2: All Alien to Me

**A lot of fluff and cute theorising mixed in this chapter because post-XX I think that's what we all need!**

Kate Beckett held her head in her hands as the car bumped along through the busy streets of central Boston. She'd pulled rank with Castle and was sat shotgun as he pouted like a child in the back seat behind Sorenson. The FBI agent was apparently oblivious to her discomfort, for which she was glad, as he concentrated on the road.

"I hate helicopters." She murmured to herself, her teeth gritted in response to her pounding temples. Beckett had always been a victim of altitude headaches, but the quick descent of the helicopter had messed with her head something fierce. The thundering in her ears was nauseating and the movement of the car was not helping her stomach to settle, she could feel bile rising in the back of her throat.

"How far out are we?" Castle piped up from the back, his eyes shifting from his paling wife to the busy road ahead uneasily.

"5 minutes, maybe less." Sorenson threw back, eyes still trained ahead.

"Kate?" Castle asked.

She looked around slowly, lifting her head out of her hands, to see him holding out a plastic water bottle.

' _small sips'_ It was advice he'd given her many times, nursing her back to health; through stomach upsets, pregnancy, bad Chinese food, and now, motion sickness. It had always helped.

' _Take small sips, it'll calm your stomach.' He said, handing her the plastic bottle before lifting her legs and sitting down beside her on the couch. Placing her legs back down over his he pulled a soft, cream blanket over the both of them._

" _For now." Kate responded, less than impressed. When she'd agreed to this somehow she'd overlooked this part._

" _It'll be worth it in the end." Castle replied with what was probably meant to be a charming smile, but in her hazy nausea-ridden state it seemed smug._

" _Says the guy without a little alien sitting on their bladder." She huffed, taking a sip of the water before placing it down on the coffee table._

 _There was beat of silence._

" _That'd be cool." Rick grinned to himself, his gaze directed away from her, distant._

" _What?"_

 _He turned to look at her, still grinning, excitement prevalent in his eyes, "If the baby was actually a little alien."_

 _Kate groaned, but there was a small smile on her lips as she pulled the pillow out from behind her head and threw it into his face._

One throwaway comment from her had created the basis of her son's childhood. From then until Felix's birth Castle had refused to stop calling the baby _'little alien'_. She'd get up in morning and he'd ask _'how's our little alien this morning?'_ When Felix had started to kick the jokes had been endless. The first time Rick had seen his son's foot pressing up against his wife's stomach he'd gasped and said, _'I'll call Ellen Ripley!'_ That comment had earned him a kick of his very own.

Over time the jokes had morphed into something more; alien plushies, constellation-covered bedsheets, brightly painted cardboard spaceships, and whispered bedtime stories about a little alien called Felix. She'd sit outside her son's bedroom door and listen carefully to tales of distant solar systems and space cowboys, not wanting to intrude or distract. Lullabies had always been her thing, but bedtime stories, they were Rick's domain, and The Little Alien was Felix's favourite. For Kate the nickname had morphed from a laughable annoyance into something truly endearing and meaningful.

It was strange that such a commonplace thing as a water bottle could remind a person so vividly of why they loved someone.

Stories. That was why she loved Richard Castle. His books. His story. Her story. The stories they unravelled to catch killers. They all merged together to create 'their story'. She doubted any couple in the world could hold a candle to it.

"Thank you, Rick." The softness in her tone was noted by both the men as she accepted the bottle of water.

"Here we are." Will pulled the car into a parking lot, talking as he navigated the vehicle neatly into a slot against the wall of the hotel, "I have an address for the grandmother. Charlestown. We should dump our bags and head over before it gets too late."

"Agreed." Kate was itching to get out of the car and go lie down, let Castle fuss over her until she fell asleep, but she had a job to do. There was a parentless and scared little boy out there and the more time they spent on this case the higher the chances grew that there wouldn't be a happy ending. She would never let that happen again; and as much as she begrudged Sorenson's presence on this case she knew that he wouldn't either.

But Castle… he knew. He'd held back her hair in the early days when she'd spent more time observing the toilet basin than at her husband, brought her coffee on the sleepless nights as the lights on the baby monitor had flashed at them, and held her hand tight on that first day of school as soon as she'd finished straightening that tiny, perfectly ironed tie. He'd been there. As much as Sorenson was dedicated, he wasn't a father. He hadn't told her explicitly, but she was a detective. When he opened his wallet there was a wedding photo, he'd made no personal phone calls since he'd arrived, and every dad Beckett knew jumped at the chance to mention their kid. He would have said something when she'd brought Felix up. Sorenson's ring finger was adorned with a modest gold band, but he didn't have any of the little quirks that came with having children. Those unconscious little looks in the rear-view mirror just to check on that sleeping face even when it wasn't there to see. The way your hands pat your pockets before you leave somewhere no matter your location just to make sure little hands haven't got to your keys. The distracted looks when you're away from home, worrying about the little things, like whether you remembered to put the drier on and left them with enough clean underwear, and the big things, like if they're going to be able to sleep without their favourite bedtime story.

And for all Castle's male pride and protective tendencies there was no way he would let it get in the way of saving little Barney Ryder.

"Kate, you coming?" Castle said as he knocked softly on the window of the front seat.

Beckett startled a little in response, "Uh… yeah."

He held her gaze, his brow creased in a worried fashion, securing the car door with a hand on the frame as she stepped out.

Will was already at the trunk, tugging out their overnight bags, half handing, half tossing them to a surprised Castle. Rick fumbled with the first bag in his desperation to catch it. The duffle almost seemed to tip out of his flailing arms in slow motion as it landed in the wet, potholed asphalt with a splash.

Rick swore. He looked up knowing exactly what famed look he was presently receiving from his wife. The intense hazel eyes paired with pursed lips created the most unimpressed stare, sure to instil shame in even the most unabashed of men.

He grabbed the bag, her bag, from the puddle and held it especially tight this time round.

"You can… borrow my pjs." He managed to mutter out, adverting his eyes to where a mildly amused FBI agent was holding Castle's own, perfectly dry, duffle. "That mine?" Castle commented quietly to himself, carefully taking it from Sorenson. Rick kept his head down as he moved toward the Hotel entrance and away from Beckett's hard stare.

She sighed, shaking her head lightly. After a moment she slammed the car door and followed the two men into the building.

It wasn't fancy. It was definitely not the worst place she'd ever spent the night by a long shot, but it didn't make the top ten either.

"I could have put us up at the Lenox you know, Sorenson." Castle stuck his hands in his pockets as he scanned the ceiling, noting the cracked, greyish appearance of the white paint at the corners.

Sorenson's nostrils flared but he didn't even glance at the writer as he approached the reception desk, ringing the bell there a little more aggressively than was strictly necessary, "As generous as that offer is Castle I am not in the habit of taking charity. This is what the FBI is paying for, so this is where the FBI agent is going to stay."

"I'm not an FBI agent." Rick said, leaning back against the desk as they waited.

"I'm well aware." Will sent Castle a thin-lipped façade of a polite smile, "And so if you wish to stay elsewhere then you're very welcome, but the car is FBI property and it's not going anywhere so I hope you enjoy your walk."

"Can I help you?" An elderly man interjected just as Castle's mouth opened to send a sharp quip back Sorenson's way.

He was slightly bent with age, a rather large pitted nose in the middle of his round, pink face. Large frames around watery blue eyes. Well-presented enough wearing a pressed, checked shirt and a friendly smile on his thin lips

"Yes," Will began confidently, then his face fell, "Uh…" He didn't know what to ask for. The thought of ordering a room for his ex-girlfriend and her husband to share was so unbearably awkward his brain had forgotten how to create sentences.

Kate rolled her eyes and strode up to the desk, "Two doubles, please." She told the man, who simply nodded with a smile and pushed his spectacles further up his nose.

Sorenson stiffened.

"After all," Castle began smugly, as the man behind the desk busied himself fetching the keys, "We've all got to do our bit to save the FBI some cash."

Beckett turned to Rick sharply, rising up on her toes to put her lips next to his ear, garnering an audible gulp from his throat, "Seriously, another word and you'll be sleeping on the floor, got it?" She whispered pointedly.

"Got it." Castle gulped again, muttering something about 'hotel carpets' and 'chaffing' as he accepted their room keys and followed her up the stairs; leaving Sorenson grinding his teeth, cheque in hand.

….

"And you have no idea who might have wanted to harm your son? Why they might want your Grandson?" Beckett softly inquired, her gaze trained on the distraught woman settled in the armchair before her, tissue in hand.

"None." The bloodshot brown eyes of the elderly, but still beautiful, Mrs Dana Ryder still seemed wide with shock at the news of her son and daughter-in-law's death. "My husband wasn't… a very present father, Simon and I were very close. I just always assumed if he was in trouble he would have told me. As for Barney…" The woman's bottom lip trembled, "I don't understand how this could happen."

"When did you last see your son, Mrs Ryder?" Sorenson's pen was poised over his notebook.

"Last weekend. Every other Sunday he brings Barney over for Lunch." The woman recalled.

"Fiona wasn't with him?" Beckett asked.

"No, but that wasn't unusual."

"How did he seem?"

Mrs Ryder fiddled with the tissue between her fingers in an agitated fashion, "Fine, at first. Normal."

"At first?" Castle leant forward in his seat. With two words he was suddenly ten times more intrigued.

"Yes," Dana Ryder began, "They were meant to stay till four, but they left early, around 3:15. I remember because I went to go check on the cake."

"Did he say why he was leaving, Mrs Ryder?" Sorenson said, scribbling in shorthand.

"No, but he left right after he finished his phone call." The woman grew even more anxious at the memory, "I took Barney with me to check on the cake. I heard the phone ring, by the time Barney and I came back Simon was saying goodbye."

Beckett chewed her lip, "You didn't hear any of the conversation?"

"No," Mrs Ryder wrung her hands, voice shaking, "but whatever it was Simon was very upset about it. He tried to hide it but I could tell he was rattled. He kissed me goodbye, grabbed Barney, and they left." The woman's voice caught on that last word.

Beckett got up, pulling out her phone and rounding the corner into the hall, she pressed the number for the boys and waited.

"Ryan." The other detective promptly answered, the buzz of the 12th precinct familiar in the background.

"Hey, I need you to run down a cell number. Find out who called Simon Ryder's cell at 3:15 pm last Sunday."

"How was he saying goodbye?" Castle said, still settled on the couch opposite their first victim's mother.

"Sorry?" Mrs Ryder's brow furrowed, confusion mixed with pain.

"Castle…" Sorenson warned.

"The tone of it what was it like?" The writer persisted.

"Um…" Dana Ryder looked between Sorenson and Castle unsurely, "Soft."

"Soft?" Will repeated, bothered by her choice of word.

"Yes. It was level, kind, but he seemed off, like he was trying to hide that he was scared. It was soft."

Sorenson didn't know what to make of it.

"So, he had a personal relationship with whoever was on the other end of that phone call." Castle concluded.

"You got that from 'soft'." Sorenson hissed.

"Mrs Ryder was there any chance your son was having an affair?" Rick said.

Sorenson looked about ready to put Castle in a headlock.

"No! No," The older woman shook her head almost violently, "Simon loved Fiona. He wasn't the type to cheat."

Will grabbed Castle's arm before he could speak again, pulling him up out of his seat and away, "What are you doing?"

"Determining that it was the victim's wife who called him at 3:15. People have very distinct voices during phone conversations. You don't even realise you're doing it but everyone's voice raises in pitch and pace when they're speaking to someone they don't know very well. Also, a 'soft' goodbye?" Castle raised his eyebrows, "I think he loved whoever was on the end of the line and the only other two people he loved were in the next room."

"And you call this detective work?" Sorenson scoffed.

Beckett strode up to them, slipping her phone into her pocket as she approached, "Ryan already had the phone records. A call at 3:12 came in from a cell registered to Fiona Ryder."

Castle gave Sorenson a pointed look, a smirk growing at the corners of his mouth.

…

"How was dinner? Did you eat all your green beans?"

The 6 year old nodded solemnly, his hand propping up his head as he stared into the computer on his father's desk, regarding his mother with a slightly guarded gaze. He'd been let down by her twice over today. A shard of intense guilt was sitting in Beckett's heart as she watched her son's eyelids flutter with fatigue.

"Alexis said I wouldn't be strong enough to play lazer tag if I didn't eat them all." The boy supplied.

"She's right." Kate smiled. Alexis was Felix's idol, there was pretty much nothing she couldn't convince the boy to do.

Felix drew his knees up and tucked his chin into the dip between them, "Where's daddy?"

"He's in the bathroom. You want to say goodnight?" Kate asked, hearing the shower turn off, and the thump of a pair of large feet hitting the floor.

Felix nodded again, his eyelids drooping as he stifled a yawn.

"Castle, your son wants to say goodnight." Beckett called.

There was another thump and a click of the lock before the man emerged, dressed only in a pair of his expensive blue boxer shorts, having surrendered his pyjamas to his wife.

"Hey, Dynamo," Rick bent over Kate's shoulder.

Felix perked up a little, "Hey, daddy, when are you and mommy coming home?" The boy's bright, hopeful eyes twisted the shard in Kate's heart sharply.

"Soon," Rick enthused.

That obviously wasn't the answer Felix had been looking for because his gaze fell and his bottom lip jutted.

"How about…" Castle decided, "You get Gram to carry the laptop up to your room and I can tell you a bedtime story?"

A small smile grew on Felix's lips and he quickly hopped down off the desk chair. The patter of eager little feet could be heard as he sped off to fetch his grandmother.

Kate threaded her fingers through Castle's where they rested on the arm of the chair she was sat in, "You can have my seat."

"You can stay." Rick suggested as she lifted herself out of the chair.

"No, Castle," Kate looped her arms around her husband's neck, his hands appearing on her waist in response, "Anyway, I'm only going to be right over there. Just… wake me up if I fall asleep before he says goodnight, okay?" She knew it was unlikely, it was still early, but she wanted to be sure.

"Okay," Castle agreed softly.

Kate drew her fingernails over the nape of his neck with one hand, the other clutching his bare shoulder. She smiled in that sweet, suggestive way that meant she wanted something very particular from him.

Rick brought down his forehead to meet hers, noses brushing, letting Kate make the final move. The way they kissed was firm and confident, the way you kiss when you know every crease and plain of your partner's lips. There was no need for exploration, this land was already mapped, but it didn't mean they didn't still manage to surprise each other. Rick slipped a hand under the shirt she was wearing, his pyjama shirt, a warm palm pressing against her lower back. Her fingers tightened in his hair as she let forth a small, stifled moan.

"Before this goes any further I feel like I should make my presence known." A familiar female voice emanated from the laptop on the desk.

Kate broke the kiss and shoved her husband away with a short gasp, "Martha?"

"Don't worry Katherine, it's hardly the worst thing I've caught you two kids doing." The woman said, laughter in her tone as she climbed the stairs, laptop in arms.

Rick groaned, "Mother."

"Hey Dynamo, I think your dad's ready to tell you that story now." Martha ended the conversation there as she placed the laptop on a chair beside Felix's bed.

…

Silence fell as Castle switched off the laptop. He walked to the edge of the bed, low city lights and flashes from passing cars fluttered against the thin fabric of a curtain that was drawn in front of the window opposite the bed.

Kate's husband was a silhouette against it, but she kept her eyes down, a bedside lamp illuminating the pages she was holding; the case file she'd spent the last 30 minutes flicking through.

"So…" Rick lifted the covers and climbed in, the mattress shifting under his weight.

"So?" Kate wasn't going to play his game.

"It's only 8:30." Castle continued.

Kate hummed in response, an eyebrow arching. She kept her gaze on the file even though she could feel his own on her face.

Castle began to wonder if something else was the matter, "You still got that headache?"

"I'm fine now." She answered. It was the truth, the pain had subsided hours ago.

"Okay," Rick laid down, but turned toward her and propped his head up on his elbow, "Because it's not every night we're somewhere where we can be _sure_ of no little disturbances."

Kate couldn't stop smiling as she chastised him, "Castle, my ex-boyfriend is in the next room."

He huffed, "It's not my fault if you're loud."

"Castle!" Kate utilised what she had at hand and rapped him in the face with the case file.

"Actually, no, I take that back, because it kind of is, isn't it?" Unfazed, he seemed overly smug at the idea of it.

"Jackass," Beckett muttered, placing the file on the nightstand, knowing she wouldn't be able to concentrate now.

Castle drew up, placing a hand between her knees to steady himself as he brushed his lips along her jaw.

"Castle," Her warning was a weak one.

Kate turned to face him and their lips met. Castle moved his arm to encircle her, pulling her down the pillows till she was lying underneath him.

"You're… incorrigible." Beckett murmured against his mouth.

"Come on, Beckett," Castle lips left her mouth to travel down her neck, his tongue flicking out to sweep light along her collarbone, "Isn't it about time we tried to make another little Castle baby."

Beckett grabbed his chin and forced him to look up at her, "I thought we were already trying?"

Kate wasn't quite sure how they'd got there, but about a month they'd discussed it. She was pretty sure it'd been playing on his mind for a while now; 7 years could be considered quite the age gap between two siblings, but until recently they'd been perfectly happy having just the one. However, Castle wasn't getting any younger and neither was she and so, though in this day and age older parents were more common, time had forced them to realise that maybe another one was something they wanted, and if they did want more it might have to be sooner rather than later.

' _Castle, have you seen my pills?' She'd been searching through the medicine cabinet for the past few minutes._

' _Which kind?' A sleepy voice echoed from the bedroom._

' _The important kind.' She almost growled, continuing to search, knocking a couple of band-aid packets and a spare toothbrush out onto the floor. 'I can't find them anywhere.'_

 _As she dug around the contents of the cabinet Rick approached, grabbing her hips from behind he pulled her into him, earning a short gasp in reponse._

' _Well then… maybe you just don't take them?' The words were muffled against her neck._

Ok, so maybe there hadn't been much of a 'discussion'.

Castle's brow furrowed, he drew away and sat up, grabbing her hands to take her with him, "We haven't been 'trying' so much as 'not not trying'."

"Eloquent, coming from the best-selling author." Kate laughed, her hands resting absentmindedly on his chest.

"What I'm _saying_ is… I think we should try _harder_." Rick grimaced at his own words, "I'm really not on form tonight."

"Babe, I want this too, but tonight's not the right time. Once this case is done and we save that little boy we can think about bringing another one into the world, okay?"

Castle visibly conceded, "Okay," He paused, "You think we have a good chance of saving Barney?"

Kate ran her hands up and down her husband's arms as she spoke in a comforting gesture, more for her sake than his, "I think so. I mean, if they wanted him dead they'd have killed him with his parents, and there's been no ransom demand yet."

"That we know of." Castle interjected.

"The FBI has got agents at Mrs Ryder's house if anyone phones her we'll know."

"While there's life there is hope." Rick quoted, as true in this context as it was in its original.

There was beat of silence.

"But does a ransom even make sense?" This case was agitating Castle more than most, though he'd been supressing it, the element of the lost 6 year old had taken all the excitement out of it and left only the uncertainty, "I mean why kill the parents if you want a ransom? Plus, there was tons of money in that car why didn't they search it? The Ryder's were running from something, maybe the killer needed them dead but didn't have the heart to kill the kid, but he was a witness so they decided kidnapping him was safer."

"That's actually…" Beckett quirked her head, "… a plausible-ish theory?"

Castle gasped, "Maybe the killer was a hired gun, an assassin paid to dispose of the Ryders after they betrayed the trust of a wealthy government official, but the assassin looks into the face of little Barney Ryder and suddenly feels filled with remorse. Torn, he takes the child from the wreckage to raise as his own, like Tom Stark and Davey Danner, using his contacts to create new false identities for himself and his young ward."

"And you've ruined it." Beckett sighed, falling back into the pillows. "Anyway, only the driver's window was damaged, it was hardy a 'wreckage'."

"Which I would have known if you'd let come to the crime scene instead of forcing me to go make small talk with Betty Crocker and co."

Kate ignored his complaint and carried on, "Simon Ryder was a high-profile prosecutor, so it's much more likely one of the criminals he put away got out, still blamed him for their time stuck behind bars, and came after him and his family."

"And chased them all the way to Brownsville?" Castle shook his head, then a spark flashed behind his eyes, "Wait! Why were they in Brownsville?"

Kate sat back up sharply, "That's not the most direct way to the border from Boston. How did we miss that?" She said, deep-seated disappointment in her tone.

"They were there for a reason, something they had to do before they left the country." Rick added.

"Or someone they had to meet?"

"And maybe that person's our killer."

 **Thank you for the amazing response to this story! Your support is the reason I keep on writing.**


	3. Chapter 3: Liquid Assumptions

"I'm Agent Sorenson with the FBI, this is Detective Beckett and Mr Castle. We're here to speak with Mr Brooks." Will gestured to them, badge in hand.

The young, dark woman behind the desk gave him a swift nod, "Yes, he's expecting you, please go right through."

Richard Castle was slow to follow the Agent as he strode off in the direction of Mr Brooks' office. Pale wood stretched out underneath the writer as he took in the décor. The offices of Ryder and Brooks were spotless and modern; constructed nearly entirely of glass and steel, even the reception desk was glass topped. Being that it was so early, just striking 7:00 am, not many employees or clients seemed to have arrived yet, and the waiting area was but a plain of leather seating and creaseless newspapers.

"Castle? You coming?" Beckett drew his attention back to the task at hand. He slipped past her in the door frame as she stood gripping the handle, holding it open for him.

"This place is… sleek." He whispered, settling on the adjective after a bit of consideration.

"Mr Brooks." Sorenson said, holding out his hand to the man behind the desk in a sign of goodwill. The man was clear suspect; Mr Brooks had a lot to gain from a dead business partner with no heir to lay claim to their share of Ryder and Brooks. With Simon and Fiona gone and Barney out of the way the firm went to him. It was best to keep him convinced that they were only here to informally interview so he'd keep his guard down.

Edward Brooks stood to accept the handshake. He was everything Castle had expected from a thirty year old, comfortable, private attorney; trimmed brown hair, a clean-shaven appearance, and a navy suit tailored to fit. However, his expression was dark, troubled, it didn't match the rest of him. Either he'd just lost his best friend, or he'd just killed his best friend.

"Agent," Brooks responded gruffly.

"Mr Brooks we need to discuss anything you might remember about Simon and Fiona Ryder's disappearance." Beckett said as she took a seat on the opposite side of the desk to their suspect. Sorenson and Castle followed suit.

"Yes, of course." The attorney settled back in his chair, fingers gripping the arms.

"Do you remember the last time you saw Mr Ryder?" Sorenson launched straight into the questions, flicking open his notebook.

"6 pm the Friday before last. I was heading home for the night, he was in his office. Nothing out of the ordinary." The man wrung his hands, concentrating on the memory.

"You didn't see him Monday?" Castle interjected.

"No, Simon called in a day's holiday for himself and Fiona."

Castle's thoughts wandered, revising the case. A sudden phone call from his wife on the Sunday, missing work on the Monday, and missing altogether on the Tuesday, all somehow resulting in the poor guy lying cold in a pool of blood on the Friday.

Kate moistened her lips, leaning forward, "How did he seem on the Friday?"

"Normal." Brooks shrugged, breathing deeply, "He and Fiona were here at 10:00, as always. Fiona left at 3:00 to pick up Barney. They were both in their offices all day."

"Mr Brooks were you aware that Mr Ryder was planning to sell his half of the company?" There was a colder look in Sorenson's eyes as he asked the question.

Simon Ryder's mother hadn't been lying when she said her son told her everything. They'd manage to follow up her tip off about Simon wanting to sell his half of Ryder and Brooks back to the accountants he'd consulted with… who'd been drawing up a quote of 850 thousand.

Edward Brooks hesitated, "I… Yes. Yes, he told me a few weeks ago."

"And you were _'okay'_ with that?" Castle probed, "Friends since college, business partners. You were just beginning to move away from criminal law and make a name for yourselves as an established executive firm… and Simon bails on you."

"Yes, I was okay with it." Brooks squirmed a little under their firm, insistent gazes, "I mean I was surprised, even a little hurt I suppose, but Simon seemed insistent... I said I was going to buy him out."

"Except you couldn't, could you?" Beckett tilted her head. She reached into her bag and pulled a folder, opening it she placed it on the desk, sliding it toward the attorney. "You recognise this Mr Brooks?"

"It's a statement." The man said shortly.

"It's a statement from your bank concerning your accounts Mr Brooks." Sorenson specified, pointing to the papers. "You lost a lot of money, care to tell us where it's gone?"

"You like the craps tables?" Castle raised an eyebrow, "Or are you more a fan of the races."

"Castle." Kate hissed under her breath.

Edward Brooks nostrils flared, "My father never believed in health insurance, 6 months ago he tells me he's been diagnosed with Thyroid cancer. You know how much that shit costs? $44,000." Castle slunk back in his seat as the man continued, "I have two kids in private school, one's dyslexic, that's another $26,000 easy. _That_ is where the money has gone."

"I'm sorry for my assumptions," Castle muttered. He was a little ashamed. Maybe he'd gotten so used to interviewing dirt bags he'd begun to assume everyone was one.

Beckett was unimpressed with Rick, she didn't even glance at her husband before continuing, "Mr Brooks I'm sorry I have to ask where you were between 11:30 and 12:15 last Thursday night?"

"Home. In bed."

"Can anyone corroborate that?" Kate asked.

"Yes," Brooks chewed his lip anxiously, "My wife, Ellie. My Secretary can give you her details."

"Thank for your time and your patience, Mr Brooks." Sorenson said sincerely, lifting himself out of his chair.

The man nodded, still a little on edge from Castle's accusations. He straightened his tie anxiously. Just as the party of three began to exit Brooks called out for them to wait.

The attorney stood up, "I heard you didn't find Barney? Is that true?" Brooks voice tremored a little, "Do you think that… maybe he's not…" He trailed off.

"It's an ongoing investigation," Beckett looked to Sorenson to see if she was allowed to carry on, he didn't stop her and so she continued, "but there is evidence to suggest Barney was wanted alive. We're hopeful."

"Just, I know that there was never anything formal, so I don't know who Barney will go to now. I want to do whatever I can to help." Brooks offered.

Beckett shared a dubious look with Castle.

"Won't he just go to his grandmother?" Rick said.

Brooks looked unsurely between the trio, garnering how much they knew from their expressions, "Well… no, Simon never managed to legally adopt Barney so won't he go into care?"

"Adopt? He's not Barney's father?" Sorenson lip parted in shock.

Brooks looked bewildered, "No, well not biologically, when Simon met Fiona Barney was already 6 months old."

…

"How the _hell_ was I not given that information?" Sorenson fumed over his espresso, "This could be a parental kidnapping, but I'm being given no information as to who Barney Ryder's biological father is."

"Espos' running down what he can, we'll know in a couple of hours at the most." Kate said wisely, sipping her latte cautiously.

"Makes you wonder what could be so important they kept it out of the unsealed records." Castle had lots of theories but so far none of them were adding up.

The coffee shop was lightly buzzing with life. A couple of tables away two young women were sat with a little boy, maybe three or four years old, he was fussing over his meal. A moment later one of the women leant over and began to cut up the boy's food into tiny pieces. Seeing the action made her think of Felix, the amount of times she'd leant over to cut up his food. Then she thought about Barney, the little boy who wasn't perhaps quite as parentless as they'd originally thought, but still just as alone in the world.

"Kate?" A warm hand covered hers.

"I'm okay." She answered automatically, sliding her other hand over her husband's.

He was stressed today, she could tell. The lack of leads on Barney's whereabouts and their distance from Felix was beginning to frustrate him more than he would let on. She'd seen it earlier when he'd lashed out at Edward Brooks; it was easy to hate people you didn't know when a child's life was at stake.

Kate phone rung, two short, insistent pings, and her hand shot over to greet it.

"Is that Detective Esposito?" Sorenson perked up, gripping his coffee cup tighter.

With just the few words that made up the text Kate's mind began to race "Yes." She breathed.

' _Need warrant for FR Witness Protection file. Give me 5.'_

"Fiona and Barney, they were in the federal witness protective relocation program." Kate looked up from her phone to meet Will's wide eyes.

"Looks like we were digging into the background of the wrong spouse." Rick concluded.

…

There was nothing of note at the Ryder's house. Everything was as if the family still occupied it, only the lack of food in the fridge and missing clothes in their closets indicated their absence.

Six hours they'd been searching, documenting, photographing, and working with the local police to canvass the neighbourhood, and nothing, not a single lead. No tales of shadowy strangers lurking in cars after dark. No stories of midnight visits from gangs of tattooed men. Nothing to get Castle's blood pumping at all.

"Brooks' alibi checks out." Sorenson strode up to Castle and Beckett where they were stood deep in discussion by the front door.

"His wife could be lying, covering for him." Castle said half-heartedly, knowing he didn't truly believe that Edward Brooks was a killer anymore. The way Brooks had offered to do what he could for Barney had been entirely sincere and void of guilt as far as Castle could tell.

"Nah," Sorenson sighed, leaning against the porch, "We have footage from a neighbour's security cam confirming him coming home at 9:00, so unless he jumped the back fence and flew to New York he didn't do it."

"Well we know Fiona went into Witness protection when she was pregnant, maybe the father's the person she testified against?" Kate suggested aloud what they were all thinking.

"And maybe he found her." Castle added.

"Maybe," Sorenson agreed, "But we won't know until that warrant comes through."

"How hard can it be to get a witness protection file opened when the witness is dead?" Rick wondered aloud, a couple of uniforms pushing past him to enter the house, "The 'protection' part is kind of bereft at this point."

"It is what it is, Castle." Kate said, leaning into him. The day had been long and dragging, the fatigue was beginning to set it. She missed Felix's warm, tight cuddles, and so she tucked herself into her husband's side; settling for the next best thing.

"So," Sorenson, for once, seemed unperturbed by Kate's obvious display of affection toward Castle, "Why don't we knock off now? While we wait for those records I can buy you guys a drink. I think after eight hours on our feet a quick break is fair."

Castle looked to Kate, she was busy thinking on the proposal, and he wasn't about to accept this particular offer without her consent. Sorenson was _her_ ex after all.

"Yeah, why not. They don't need us here anyway." Beckett gave Castle's arm a squeeze of reassurance. "And I need to sit down." She muttered as she walked down toward the car.

…

"Right," Castle clambered off his stool, losing his footing a little, "I need to go to the little boy's room."

Sorenson watched the man as he walked away with a mixture amusement and confusion playing on his features, "He hasn't had the many… has he?"

The bar hummed around them. It was an intimate 'nook and cranny' kind of place, no more than 15 people were huddled around the tables. One barman, a middle-aged guy in a red muscle shirt and apron, stood behind the bar.

Kate was struggling not to laugh as Rick stumbled through the bathroom door, "No, Castle's just a lightweight."

There was a pause. It was less awkward than Kate might have imagined but still stale air hung between them.

"Kate, I'm glad you're happy." Will couldn't quite bring himself to look in her eyes as she said it.

Beckett smiled sincerely at him, "And, are you?"

Looking up at her his eyes were bright, a smile burgeoning, "I am. Libby's… incredible. We may not have everything, but we're happy."

"You miss her." It was a statement, not an inquiry.

Will moistened his lips, his smiled saddened. "She's a journalist, she works from home mostly so she travels with me, but she's in India at the moment."

"A writer?" Kate bit her lip to stifle a laugh, "That's… yin yang, Castle was right."

"What?" Will eyebrow's knitted in his failure to comprehend.

"Nothing." Kate waved the comment away, grinning.

"I know you miss your son too." Will said, running his finger along the rim of his depleted glass. "Whenever we pass a little boy on the street you… you get this look in your eyes."

"I didn't even realise." Kate's voice was quieter now. Felix would probably be getting ready for bed now. Martha or Alexis would be tucking him in, but it should be her, it should be her and Rick.

' _There it is again.'_ Sorenson thought as he studied her face.

"Felix? Right?" The Agent tilted his head at her.

"Yeah." Kate Beckett pictured him as soon as his name was said. Seeing dark hair and shining green eyes in her mind's eye as clear as if he were stood in front of her.

"Can I ask why 'Felix'? It's a little unusual."

"After Felix Leiter." Kate was almost embarrassed as she said it, but not quite, she still thought it was sweet, "The American spy in James Bond. It was Castle's idea."

There was laughter in Will's voice as he spoke, "Can't say I'm suprised."

"Casino Royale was the book that inspired him to write the Derrick Storm series. It was important to him… and I liked the name." When she'd been pregnant the name Joseph had played on her mind nearly every day, but when Felix had been born it just didn't fit, and she hadn't wanted to do it out of obligation. If Kate had said she wanted it then Rick would have folded without a second thought, but she hadn't, Felix was Felix, and she'd never have any regrets about that.

There was a beat of silence.

"You know there's really no point us staying us Boston any longer." Will said, draining the dregs of his beer. "We've done everything we can here, there's no reason we can't head back to New York tonight."

Kate examined his face closely, he wouldn't look at her but it was like he was reading her mind. Was her pining really that obvious?

"You think?" Beckett's tone was hesitant.

"I think we've established that the perp is most likely someone they went to New York specifically to meet with, the APB we put out on Barney hasn't flagged. It's likely that they're still in New York, and that Barney's still in New York, so that's where we should be."

"Will, I'm a professional, I can handle being separated from my family for more than a few days." Kate didn't want him cutting corners for her, no matter how badly she wanted to go home.

"I know Kate, and I honestly think New York is where we need to be." Sorenson seemed sincere, "Anyway, you're not the only one I'm worried about." The agent glanced at the restroom door out the corner of his eye.

"Castle?" Kate's eyebrow shot up. Will Sorenson was worried about Castle?"

Sorenson chuckled nervously, "I know this case has got to be hard on you two. Look, Kate, Castle gets on my nerves, sure. But there's three things I know for sure about him; he cares about you, he makes you happy, and he helps you close cases quicker than any other cop in the city. Except, right now he's on edge. He's worked up about this, even I can see that. I think you both are. I'm thinking maybe when you're back with Felix you'll be able to focus better, solve this case quicker."

Kate gritted her teeth, "I'm fine Will. You think I can't do my job because Castle's distracted?"

"Jesus, Kate. You're only human." Sorenson's fists were clenched on the table top, "Besides, that's not what I'm saying. I'm saying that we've been through this before, a little six year old boy disappearing in the middle of the night, and it ended badly. I'm saying that I know you're scared of how this is going to end, and I'm trying to tell you that you don't always have to be so strong, everyone else is scared too. You think that with Felix as part of the picture losing this little boy could hurt way worse, I get it. You're wondering what it would be like if it were Felix in his place, about your mom and how you have to prote-"

"You don't get to tell me what I'm feeling, Sorenson." Beckett bit back sharply before he could finish, her walls going up.

"Everything okay?" Beckett and Sorenson were locked in a staring match when Castle returned, sitting back down on his stool.

"Course," Sorenson responded, breaking from Beckett's hard gaze, "What would you say to another round, Castle?"

Rick smiled at Sorenson for the first time since they'd been reacquainted, "I'd say you're very kind but I'm going to have to insist on buying this one."

"How could I say no to that?" Sorenson nodded, "But I'll come with you, I want to see what other bitters they've got."

"Be my guest." Rick gestured for Will to lead the way as he climbed off his stool once again, "You okay, Beckett?" Castle asked his wife softly as Sorenson approached the bar.

"Fine." Beckett murmured, her thoughts still pondering lost little boys… and motherless little girls.

Castle knew that look and decided not to push it, simply following Sorenson in haste without another word.

…

Castle had been jittery ever since Kate had told them they were going home, and now they were at the front door he could barely contain himself.

Rick had never been one for homesickness, but there had been plenty of occasions where he'd found it hard being away from his children.

Kate recalled those first few weeks after Alexis had gone away to College, the girl had stayed nearby but still Castle had been worried, distracted constantly; making breakfast for three only to see Martha descend the steps of the loft alone and remember Alexis' absence.

He'd nearly cancelled the first book tour he went on after Felix had been born, but Kate had convinced him he needed to go. The second he'd fallen back through the door two weeks later, bags dumped without a thought, he'd almost flown to his son's crib. Felix had been so small then, just 5 months, and still sleeping some nights in his parent's room.

 _The movement caused Kate to stir, waking, still groggy, eyes adjusting to the dark to find a familiar shape bent over their son's sleeping form._

' _Hi, Felix,' He whispered, bringing his face down to brush his lips against his baby's delicate brow, "I missed you… I love you, Felix."_

 _She watched for a while as he drew the back of a finger down Felix's round, little stomach. The baby's mouth opened in a round 'O' and closed again._

" _Hey?" Kate said, just as quietly, Felix was sleeping soundly and the last thing she wanted was to spend Rick's homecoming trying to lull a grumpy baby back to sleep._

" _Hi, I thought you were asleep."_

 _Kate hummed in response, she was tired beyond words. Working full days on top of being a temporarily lone parent was exhausting. She closed her eyes, only meaning to do so for a moment, she found she could hardly bare to open them again._

 _She heard him shift, quiet steps and the muffled rustle of clothing being removed. A weight dipped the bed as he clambered in beside her, rolling over to curl himself, warm and firm, around her. Not bothering to search in the dark for his pyjamas he'd elected to wear just his underwear. She curled into him, tucking her legs in so her heels were against his bare shins. His chest pressed against her back, she could feel his heart beating, rhythmic and comforting._

 _He sighed, breath hot at her neck, "I missed you too."_

"Home sweet home." Rick opened his arms wide and breathed in the loft, "Is it too late to go say goodnight?"

The space was completely silent but for the hum of various appliances and the occasional sound of vehicles passing down in the street. The street lights were all the stopped the black from taking hold.

Kate pondered the little boy sleeping upstairs, "It's late. If we wake him up now he'll never go back down."

Rick's shoulder's slumped, knowing she was right.

Beckett was just as disappointed at her words as he was, but she was determined to see things in a brighter light. The Ryder case was a dark enough presence in their lives without bringing some different form of darkness home with them. She wouldn't let Sorenson's words be the truth, though she secretly wondered if maybe they already were.

"Just think how happy he'll be to see us when he comes down for breakfast tomorrow." Kate slung her arms around her husband's neck, bright eyes searching his for that spark she knew so well.

It appeared suddenly, dancing amongst the blue, "I'll make s'morelettes." He whispered excitedly.

Kate began a low groan, no doubt planning to derail his breakfast plans with a swift _'No, Castle.'_ , but the Rick drew his arms tight around her, dipping his head to kiss below her ear, and she forgot her disapproval almost immediately.

…

 **Twists and turns. Castle isn't Castle without them… I hope you guys like where I'm going with this story.**


	4. Chapter 4: The Good Knight

"And I'm gonna learn Mandrine. I've decided." The little boy told his father confidently, shovelling another chunk of s'morlette into his mouth. His words were muffled as his breakfast collected in his cheeks. Melted chocolate gathering at the corners of his mouth.

"You mean Mandarin, as in the language?" Castle was unperturbed by the statement as he bent over the stove, spatula in hand; just last week the boy had announced he was going to learn how to do karate. Which, as it turned out, had merely been an afternoon of him running around the lounge in his bathrobe with a comically serious expression repeatedly kicking the couch.

"Yep!" Felix popped the 'p', following it up with a confident, chocolaty grin.

"You are, huh?" Rick jostled the pan in his hand, sliding the s'morlette from rim to rim.

"Yeah, my friend Cal speaks it. He said I should learn it so we can have super-secret conversations. Like spies!" Felix added excitedly.

"Sounds awesome, Dynamo." Castle said, distracted as he scraped the spatula he was holding across the base of the pan, flipping its contents onto a plate.

"What sounds awesome?" Kate Beckett appeared from the bedroom, practically gleaming she looked shiny, already in a crisp dark pant suit with a white shirt underneath.

Before Kate could get close enough to kiss him Felix had jumped from his stool and scuttled over to his father.

Kate froze, heart plummeting, her stomach flipping in disgust. Had her own child just… run away from her?

"Daddy! I need my stool!" The boy bounced on the balls of his feet impatiently.

"Uh…" Castle spun around, seeing the blue, plastic booster step tucked in the corner at the base, he kicked it over to Felix.

The kid promptly copied his dad, managing to nudge the step toward a nearby section of the counter with the force of his foot. He clambered up speedily, pulling aggressively on the tap, proceeding to scrub his breakfast-coated hands and face. Then he grabbed a dry washcloth, running it roughly over his mouth.

"Felix?" Beckett took a step toward him, still unnerved.

Felix hopped back down and, much to Kate's relief, sprinted over to his mom. He wrapped his arms around her midsection, nuzzling into her, she could feel his breath on her lower abdomen. His hands were clutching at her blazer as tight as a vice.

"Felix, what was all that?" She asked tentatively.

"So my cuddles aren't mucky." He said it like it was obvious, his face still pressed against her.

"Seriously," Castle raised a brow jovially as he stabbed a fork into his s'morlette, "One day with Alexis in charge and suddenly he's all prim."

Felix only gripped his mother tighter at the mention of her absence.

He was being needy. Felix was a lot of things; stubborn, creative, precocious, maybe a little loud, sometimes a bit moody, but he was rarely needy. Until the age of 5 the kid had been surrounded by adults all day almost every day, except for the few hours a week he spent in day-care. His mother had a full-time job that forced her to be absent at odd hours. There had been no other children to play with, and even with Castle as a father there'd been plenty of the times the boy had spent hours entertaining himself as his dad wrote. As a result Felix was resilient, and fiercely independent.

Kate knew what this meant. It meant she was in too deep. Felix didn't care about the hours, sometimes the days away, he was used to that. It was the distance in his mother's eyes when she was looking right at him that told him something was up. He'd seen it this morning when he'd woken up to find her home, and already making coffee in her pyjamas.

" _Mom?" He dislodged sleep from his gritty eyes as he descended the stairs, barely awake, and still in his sleepwear; a superman top matched precariously with pants covered in brightly-coloured dinosaurs._

 _The earthy, dark smell of coffee was hanging in the air. The fan on the stove whirred away softly, sending the heady smell scattering over to him. Felix gripped the banister as the woman spun round to regard him._

" _Felix, you're up." Her voice was warm, always comforting, like a mothers voice is meant to be. A tone of speech she employed just for him._

" _Mommy?" His feet led him down the last couple of steps, quicker and faster, almost slipping in his hurry._

 _She abandoned her coffee mug and strode over, picking him up in one clean scoop, placing him on her hip, holding his warm body as close as possible to hers, "Hey baby, I missed you. I…" Her mouth parted as if to continue, but then it closed. Silence._

 _Felix's forest green gaze met her hazel one, full of far too much for such a young child._

 _The little boy placed his small hand on her neck, his fingers gently finding her pulse. He remembered his dad telling him, 'See. Put your fingers there. Can you feel it? That's your life, Dynamo. That's your life. It's beating underneath your fingers.' Felix did it almost involuntarily. The look in his mother's gaze was one of love, always, but it was veiled. Guilt clouded, building a wall, drawing a curtain between mother and son._

 _A dent appeared between Felix's eyebrows, "You're here, Mommy?" He didn't falter, didn't hesitate, his features hard and set like Castle's were when he was hurt, when it was deep and personal, when she'd hurt him. It'd been a long time since she'd seen that look, but it was an impossible one to forget._

 _The words threw Kate. She recalled her own father's words of wisdom from when Felix had been a newborn, wailing red-faced in his inexperienced and fearful mother's arms, 'Kids can sense things, Katie.'_

 _Kate's lips parted, "I…"_

She needed to solve this, but she was hurting Felix in the process. Every time she saw him a small voice in the back of her mind asked, _'what if?'_ She squeezed her eyes shut, trying to banish the thought from her mind, but its strength only grew. _'What if Felix was Barney?' 'What if I died?' 'What if Felix was alone?' …_

' _What if he ended up like me?'_

Looking inside she could see it, that tiny part of herself she'd tried put to bed years ago after it nearly tore everything apart. The part of her that just couldn't give up and move on. Katherine Beckett was as stubborn as they came, but it wasn't about pride, it was rooted in failure… the heavy sickening feeling in the pit of her stomach, sitting across from a grieving child to tell them you couldn't do it, you couldn't catch the person who ruined their life.

Montgomery had once told her, in an intonation that to this day stayed with her, sending chills across her spine, _'We speak for the dead. That's the job. We are all they've got once the wicked rob them of their voices. We owe them that. But we don't owe them our lives.'_

She'd never had a chance to ask him… What about the living? What about those that have to go on knowing every day that somewhere out there that wickedness walks free? A life for a life saved, was that worth sacrificing? She didn't want to think of Felix obsessing, risking, and losing what she had.

"Are you okay?" Felix's question reached her, arms still secure around her, face upturned now as his chin rested against her stomach.

"Kate?" Rick said, silently reiterating the question from behind the kitchen counter.

She ran her fingers slowly through Felix's dark hair, her other hand coming to hold his jaw, a thumb running gently over his rounded cheek.

"Yeah." Her voice was barely more than a whisper. She knelt, his arms loosening to let her, "We have to go now."

"I know." The boy said, blinking, lips pursed and down turning.

"I love you." She took him by the upper arms and pulled him in, pressing a lingering kiss to the lobe of ear, his temple, his brow.

…

"Hey." Sorenson flinched at the sight of her, they'd barely spoken since he'd accused her of being too emotionally invested in this case, and he wasn't completely sure where he currently stood. The conversation on the journey home yesterday had consisted mainly of short, calculated 'can you pass that's and 'what the time's, and nothing more. If Castle had noticed, which Beckett suspected he had, he didn't say a word.

As they'd reached the floor, stepping off the elevator, just moments ago, upon seeing Sorenson, he'd mumbled out a quick excuse to give her a minute with the FBI agent. Heading over to make coffee in the break room, despite them having had a cup not more than an hour ago.

"Hey." Beckett's voice nearly cracked as she spoke but she covered it up with a sigh, perching on the edge of the desk beside him.

They sat in the quiet, the light hum of the precinct coming to life around them. Each person pretending to read the murder board in front of them.

"Kate I-" Will finally started.

"I need to apologise." Beckett spoke over him, rubbing her brow roughly, "I shouldn't have reacted the way I did."

"No," Will's teeth were gritted in acceptance, "I stepped over the line."

"Maybe," Kate sucked in a breath, standing up, folding her arms in tightly, she dragged her gaze from the floor to look him in the face, "but you did it to tell me something I needed to hear."

Will waited, jaw squared.

"I am too close to this." Kate nodded, turning to observe the murder board. The face of little Barney Ryder stared back at her. It was a school photo, there was a wide smile reaching all the way up to his glittering blue eyes.

"I want to protect him too you know." Sorenson said gruffly, standing up to join her.

There was a guarded nature to his tone, an element that promised something more than he was telling her. He was invested in this case too, more than she could know.

"Never doubted it." This time she looked him in the eyes with no apprehension.

…

"Alright, ladies and gentlemen. Hold onto your socks." Ryan announced with vigour, striding over, Esposito at his side, to where the rest of the team were huddled around the murder board waiting. "The DA's office finally got round to signing off on the witness protection files."

"So we finally know who Fiona Ryder actually is?" Castle inquired anxiously, fingers itching to crack open the promising, federally stamped file in Ryan's grip.

"And that's not the best part." Espo was quick to tease, nudging Castle with his elbow.

Sorenson leant back against Beckett's desk, quietly enjoying the scene playing out in front of him.

"Yeah. No doubt, you're going to love this one Castle." Ryan agreed, joining in.

"Definitely up your street, Bro." Esposito nodded knowingly, supressing a grin at Castle's frantic and expectant stare.

"Oh God, please put him out of his misery." Beckett rolled her eyes. Teasing Castle was always fun but she was nearly as desperate as he was to find out what the contents of the FWP file was.

"Two words:" Ryan paused to whip a picture out the file and slap it on the murder board, "Mrs O'Doherty."

The old photo looked to be a good seven years old. Fiona Ryder was younger, barely 23 years old, wide blue eyes and shorter hair that reached to hover just above her shoulders. It was difficult to determine the attractiveness of a corpse, the pallid nature of their skin, the blank eyes, it all made it hard to imagine them as once beautiful. But, in this image, in her youth, Fiona Ryder had been very, very beautiful.

"Specifically," Esposito furthered, "Mrs Aislin O'Doherty, maiden name Maguire."

"O'Doherty?" Sorenson stood sharply, as if shocked, moving closer, "I know that name…"

"The O'Doherty family," Castle spoke with the sure voice of a man who was well-versed in his New York mobsters, "They were a very successful off-shoot of the Westies."

"Were?" Sorenson picked up on Castle's use of past tense, concocting a story in his mind of their fall, and Fiona's part in it.

"'Mrs?'" Kate repeated Ryan's careful choice of address, "She was a wife of one of the Westies?"

Espo scoffed, "Not just any one of the Westies. Nine years ago she married Sammy O'Doherty Junior. Heir to the whole shebang. Then she copped him out along with a load of his cronies just over six years ago. She had enough damaging evidence to take down half the family. Got Sammy locked up for 7 years supposedly."

"Supposedly?" Sorenson turned to regard Javier.

"He got out on a technicality just over a year ago."

"Long enough to find Fiona, especially with his resources. The Irish Mob have connections across the US, maybe even moles in the government." Beckett added.

"And I'm guessing Mr O'Doherty was the type to hold a grudge?" Castle's expression was grim.

"That's not all." Ryan drew another photo out of the file to place next to Aislin. It was of a young man, generically handsome but for a strange bump in his nose that told the tale of a desperate fist fight followed by the refusal of medical attention. His dark eyes were a murky green, mouth set in an angry line. Short dirty blond hair sprouted thickly from his scalp. "Based on our timeline… it's safe to assume Fiona… Aislin, sorry, was still married to Sammy when Barney was conceived." He finished, delicate in his demeanour.

"It all makes sense," Castle murmured, moving closer to the board, "Fiona knew this was going to happen, she knew she was going to have to run. She told Simon and they set up the plan to escape where the Westies couldn't ever reach them. That call on the Sunday was her telling Simon it was time." The writer marvelled over the surreal nature of the story. "And, of course Barney was _taken_ , Sammy wouldn't kill his own son. He wanted his son, and he wanted revenge, that's what this is all about!"

"Okay, Sherlock, but why were they in Brownsville? That's not Westie territory." Kate watched her husband, amused, quietly revelling in his enthusiasm.

"I don't know, Watson, but I'm going to figure it out." Castle smirked at his wife playfully.

"Shouldn't Beckett be Sherlock," Espo rebutted, arms crossed, "Since, you know, she's the actually the Detective."

"And, let's be honest here Castle," Ryan slapped the man on the back in a gesture of solidarity, "You've always been the sidekick."

"I resent that." Rick shot back, shrugging Ryan's hand from his shoulder.

"Guys, I'm happy for you to discuss this in your own time," Sorenson re-joined the conversation, trying to keep his expression as stony as possible, "But right now we have a suspect to pick up."

…

"I didn't do it." Sammy O'Doherty Junior leant loosely back in his chair, seemingly assured in himself. Sorenson circled him like vulture in the tiny interrogation room, letting Beckett stare him down from her position on the other side of the table.

The boy was a man now, a couple more lines around his mouth, his hair longer.

"What didn't you do?" Beckett rested against the glass, arms folding.

On the other side Castle and the boys watched intently, taking note of every twitch of O'Doherty's face.

"I don't know." Sammy shrugged, "Whatever it is you dragged me down here to accuse me of."

"Murder." Beckett answered shortly, she had a feeling the best way to get through to this guy was through straight-forward talking, and quickly, before he pulled the 'I don't have to talk.' card.

"Murder?" Sammy's eyes widened, lips parting, "Look, I don't know anything about a murder." He looked a lot less relaxed now. Staring 25 years in the face will do that to you.

"Really, because you knew the victim." Sorenson stated, slamming the photo of Fiona Ryder, the former Aislin O'Doherty, down on the table in front of Sammy.

"Aislin?" Sammy brought his fingers to meet the image, "Aislin's dead?" The shock in his voice seemed real enough, but being a mobster's kid and being a good liar sort of went hand in hand.

"Nice try, Junior." Sorenson sighed. "You know when I was up in Boston I talked to Aislin's son's school. Someone mentioned a man matching your description hovering around the gates a couple of weeks ago." Will's tone was sharp, accusatory.

Beckett moved toward the table, settling in the seat across from O'Doherty, "So what happened, Sammy. The betrayal of her ratting you out to the cops, all whilst pregnant with your son, just too much for you to handle?"

The man scoffed, turning his gaze to the floor.

Beckett carried on, "Did you get angry? I mean, that's understandable, she took Barney away from you, didn't even give you a chance to know him. She got you locked up for six years of his life. Then when you track her down she's happily married, raising your kid with another guy, that's got to hurt."

"Okay, so what if I went to see him." Sammy hissed, "It's not a crime. I went to see if it was true, I got a tip off saying she had a kid old enough to be mine, so I went to check it out."

"Where's Barney, Sammy?" Sorenson said, jaw set.

"I don't have the damn kid, okay?" Sammy yelled, bring his fist down harshly on the table top, "And I didn't kill Aislin. I went to see her, that's all. I told her I didn't blame her for copping me out, she was manipulated, I knew that then and I know it now. I just wanted to know if the kid was mine. She explained that he wasn't, so I left."

There was a pregnant pause.

"Plot twist." Castle whispered to a transfixed Espo and Ryan as they watched from the other room

"You're… you're not Barney's father?" Kate's shoulders slumped. They just couldn't seem to catch a break in this case.

"No," Sammy looked between Sorenson and Beckett, noting their dubious expressions, "Can't say I was surprised, last few months before she ratted me out I thought she was having an affair, she kept sneaking out and avoiding me, but then I ended up in police cuffs so I figured that's what she'd been up to. Looking back… maybe it was both."

"Why'd you say that?" Sorenson finally settled down in the seat next to Beckett.

"Look, it's not me, but I know who the kid's dad is." Sammy leant a little further across the table, "The guy who sent me down, who turned Aislin against me. That bastard lawyer, Reilly Kane."

Sorenson scrawled down the name and promptly exited, the door slamming in his wake.

"Mr O'Doherty where were you last Thursday night between 11:30 and 12:15." Beckett was less and less sure by the minute that this was their killer, but she had to ask.

"Uh… a bar just off central park, with my friends, playing some pool. I can give you names… Jonah Locke and Freddie Hogan."

"Detective I'm afraid we're going to cut this short!" A short, dark-haired, ordinary-looking man in a crinkled black suit entered the room with vigour, the door slamming harshly against the wall.

"And you are?" Castle was at the door in a flash, a determined expression on his face. Ryan and Esposito crowded behind him, back up, as always.

"Anderson Kelly. Mr O'Doherty's lawyer," The man shot Sammy a short look, "and I'm advising him to say absolutely nothing from this point forward. If you don't have probable cause to hold my client then I'll be taking him now."

Beckett didn't move. Sammy had given her everything she needed, even if his story checked out they had another suspect now; Barney's 'supposed' biological father. Reilly Kane. Though with their current luck it may just be another red herring.

"Okay then," Anderson Kelly grunted, grabbing O'Doherty's arm roughly, pulling him out of his chair, "Sammy, we're leaving."

O'Doherty had the look of a kicked puppy as he solemnly followed his family lawyer out the door. Castle watched them move toward the elevator intently, only drawing his eyes away when they disappeared from sight.

He looked to his wife, a newfound spark of hope in his eyes, "Reilly Kane?"

"Reilly Kane." Beckett sighed forcefully, giving her husband's arm a quick squeeze as she walked by him.

…

"I mean this case is like a god damn Russian doll." Castle complained. There was a rush of hot air as he opened the oven, pulling a steaming tray of seasoned chicken from it's depths.

"Richard!" Martha scolded, jerking her head in the direction of Felix, who was immersed in his colouring. Too busy roughly dragging a pathetic looking red pencil over the paper to pick up on his father's faux pas.

Kate smiled at Castle's frustration as she collected the cutlery, "Well, I have a good feeling about Kane. I think we're going to find Barney soon."

"You really think so?" Rick carried the meal over to the table, placing it on the grate in the center.

"I hope so. Third time lucky I guess." She straightened a fork delicately as she spoke.

Rick removed his oven gloves, dropping them on the table cloth unceremoniously. "Worked for me." The words rumbled in his chest as he came to stand behind Kate, wrapping his arms firmly around her midsection as she laid up the table. Felix and his mother were facing the other way so he chanced a soft kiss to the smooth, bare skin at the base of her neck.

"Ew." A small voice announced from the counter.

Martha's laugh tinkled, echoing off the walls, at her grandson's unimpressed reaction.

Both husband and wife looked up to meet their son's gaze. They tried to keep the displays of affection PG around Felix, but he was still pretty used to them getting a bit handsy. He'd been perfectly okay with it until about a year ago, when he'd started school, then suddenly he'd begun acting as though it were crass and inappropriate. Making faces as they kissed, though a glittering, playful light shone in his eyes making it clear to them that it was all just a big act. Castle suspected one of the kids in his class had given him the 'kissing is gross' talk.

Kate's hands slipped over Rick's, ready to pry his hands from around her, but Castle only held her closer, harder. Beckett tried not to laugh, abandoning the half laid cutlery as she tried to wriggle from his grasp.

"You know, one day, Dynamo, you're going to be so very thankful for how much your mom and I love each other." Castle told the boy, confident and assured in his words, his hands going further around Kate as he spoke. He began to nuzzle into his wife's shoulder, both of them desperately holding back laughter. Beckett played along, just barely struggling to escape.

"Dad! Mommy!" Felix yelled, his hands going up to cover his eyes, a giggle building.

"Okay Kids, I think that's enough emotional trauma for one evening." Martha joked, clapping her hands to get their attention, "Should we eat?"

"We should." Beckett said, tears in her eyes when she finally broke free Rick's grip. "Felix, can you go fetch Alexis and wash your hands please?"

"Yup," The boy was off his seat and up the stairs like lightning.

"So…" Martha said, sitting down at the table as Rick began to serve up, "are you really that positive about finding this boy or was that all an act for Felix?"

"I…?" Kate was positive, wasn't she? She hoped it was only Martha second guessing her that was sowing a seed of doubt in her mind.

"Mother…" Rick warned, passing the older woman her plate of food. Martha became suddenly very aware of the cornered look in her daughter-in-law's eyes.

"Oh, Katherine, Darling, I wouldn't ask if it weren't for Felix." Martha specified, a rare, wise and solemn edge to her tone, laying a warm hand over Kate's where it rested on the tablecloth. "You and Richard have both been so distracted the past few days, with the mentions of this other little boy constant, it's no wonder the kid has caught on that there's something a little different this time."

Kate was suddenly struck down by guilt, she was usually so careful about referencing cases around Felix, "Martha, I didn't mean to make him uncomfortable-"

The woman held up a hand to silence Kate, "I'm not in any place to tell you how to parent your kid-"

"That's true." Castle muttered, as he neatly sliced up Felix's chicken.

"Not the time, Richard." Martha pursed her lips at her son's comment before continuing, "but I am warning you, Katherine, that you two have brought this story to his attention, knowingly or not, and one day soon he's going to want to know the ending. And, if it's not a happy one you're either going to be breaking that little boy's heart, or lying to him."

Kate's heart clenched. She'd messed up, she'd made all the mistakes she'd promised herself she'd never make with Felix. At six years old everything has a happy ending, the good knight always wins, except reality doesn't work that way. Sometimes the villain got away… and sometimes he didn't, but it hardly mattered, because it was already too late to save the innocent.

She needed this over. She'd needed to find Barney Ryder, and soon, for everyone's sake.


End file.
